Shin Nishiyama

High-speed recovery of antimony using chelating porous hollow-fiber membrane

A porous hollow-fiber membrane containing an iminodiethanol (IDE) group as the chelate-forming group was applied to the recovery of antimony in the permeation mode. An antimony solution was forced to permeate through the pores of the chelating porous hollow-fiber membrane, driven by a transmembrane pressure. The membrane with a thickness of 0.7 mm and a porosity of 70% had an iminodiethanol group of 1.6 mol/kg of the membrane and a water flux of 0.95 m/h at 0.1 MPa and 298 K. The breakthrough curves of antimony overlapped irrespective of the permeation rate of the antimony solution ranging from 2 to 20 ml/min, i.e. the residence time across the membrane thickness ranging from 3.4 to 0.34 s, because of negligible diffusional mass-transfer resistance of the ionic species of antimony to the iminodiethanol group. At antimony concentrations below 10 mg/l (pH 4.0), a linear adsorption isotherm was obtained. The adsorbed antimony was quantitatively eluted by permeation of 2 M hydrochloric acid through the pores of the membrane.

Removal of Antimony (III) Using Polyol‐Ligand‐Containing Porous Hollow‐Fiber Membranes

ABSTRACT A polyol-ligand-containing porous hollow-fiber membrane capable of removing antimony (III) from a liquid stream was prepared by radiation-induced graft polymerization of an epoxy-group-containing vinyl monomer, glycidyl methacrylate (GMA), and subsequent functionalization with N-methylglucamine (NMG) and 3-amino-1,2-propanediol (APD). The resultant chelate-forming group density was 1.6 mol per kg of the NMG-group-containing porous hollow-fiber membrane. An antimony (III) oxide solution (10 mg per L, pH 3.6–13) was forced to permeate through the submicron-diameter pores of the chelating porous hollow-fiber membrane. The antimony concentration of the effluent penetrating the outside surface of the hollow fiber was determined as a function of the effluent volume. The breakthrough or dynamic adsorption capacity for antimony was 54 g of Sb per kg of membrane at pH 11. Because of negligible diffusional mass-transfer resistance, the breakthrough curves overlapped irrespective of the permeation rate of the antimony solution across the chelating porous hollow-fiber membranes.

Short range structure of B2O3–Cs2O glasses analyzed by x‐ray diffraction and Raman spectroscopy

Structural analyses of pure B2O3, B2O3(90 mol%)–Cs2O (10 mol%) and B2O3 (80 mol%)–Cs2O (20 mol%) glasses were made by an x‐ray diffraction method and the effects of Cs2O addition were investigated on the short range structure of the glasses. Furthermore, Raman spectroscopic studies were applied to analyze the interatomic interactions between boron and oxygen atoms. Due to x‐ray diffraction, pure B2O3 was confirmed to have BO3 triangles which formed the so‐called boroxol ring structure. When Cs2O was added to B2O3, the boroxol ring structure still remained but some parts of BO3 triangles was definitely converted to BO4 tetrahedra. This result was also supported by Raman spectroscopic observations. The other important consequences were that a Cs atom was surrounded by six O atoms, and four Cs–O interatomic distances were about 3 A but two pairs 3.5 A, indicating that the distorted Cs–O octahedra might exist in the B2O3–Cs2O glasses. This spatial arrangement of Cs and O atoms was quite different from the cor...

Pulsed neutron diffraction study on the short range structure of B2O3-Ag2O glasses

Abstract The short range structure of (1− x )B 2 O 3 – x Ag 2 O ( x =0.05–0.30) glasses was investigated by time-of-flight neutron scattering experiments. Radial distribution analyses were applied to extract the structural information, but the structural parameters for each atomic pair were finally optimized in the Q -space. The bond distances of near neighbor B–O pairs were estimated at 0.138 and 0.145 nm, and the corresponding coordination numbers were 3 and 4, respectively. These were ascribed to the B–O correlations in distorted six-membered rings consisting of planer trigonal units and tetrahedral ones. The silver atoms serve to hold the networks together through coordination with oxygen atoms, thereby the nearly octahedral arrangements of oxygen atoms around a silver atom were found to exist in these glasses. The octahedral units were distorted to such an extent that the Ag–O distances were ranging from 0.25 to 0.32 nm. The existence of medium range order was also confirmed in the structure factor S ( Q ) over the composition range of this work.

Characterization of perovskite-type GdFeO3 powders prepared by amorphous citrate process

The purposes of this study were to obtain GdFeO 3 powders by calcining their precursor gels which were prepared from Gd 2 O 3 and Fe 2 O 3 by the amorphous citrate process, and to characterize the powders in comparison with those prepared by the solid-state reaction (SSR) of Gd 2 O 3 and Fe 2 O 3 powders. Furthermore, it was attempted to estimate precisely crystallite sizes and lattice constants of GdFeO 3 powders by x-ray diffraction line profile analyses

X-ray diffraction study on the short-range structure of K2O–TeO2 glasses and melts

Abstract The short-range structure of K 2 O–9TeO 2 and K 2 O–4TeO 2 in amorphous states such as glass and melt has been investigated by X-ray diffraction (XRD) and semi-empirical molecular orbital calculation (AM1-MOPAC method). The structure of amorphous alkali tellurites consisted of the TeO 4 trigonal bipyramids (tbp) and the TeO 3 trigonal pyramids (tp). Confirmed in the present work is that the TeO 4 trigonal bipyramids characteristics of TeO 2 -based glasses transform into TeO 3 trigonal pyramids with increasing modifier K 2 O content and a rise of temperature. The usage of XRD and MOPAC enabled us to comprehend in some details what to happen in phase transition from glasses to melts.

X-ray diffraction study of the short-range structure of LiCl–Li2O–TeO2 glasses

Abstract Structural analyses of amorphous LiCl–Li 2 O–TeO 2 were made by X-ray diffraction. The basic structure of the tellurite glasses consisted of the TeO 4 trigonal bipyramids and the TeO 3 trigonal pyramids. The resulting structure was in agreement with that so far analyzed by infrared spectroscopy. The effects of LiCl addition on the short-range structure were also discussed according to the mutual use of the radial distribution analysis and the correlation method in this work.